Aqua Kleen AK-8002 Unicel Replacement Filter Cartridge for Swimming Pool and Spa 75 sq. ft., 10 1/16" OD, Open Hole: 6" Top, Open Hole: 6" Bottom, 16 1/8" Long, AK-8002 Exact Fit for Unicel: C-9407 Exact Fit for Pleatco: PAP75-4 Exact Fit for Filbur: FC-0685 Guaranteed Perfect Fit - Extremely Durable - Wash & Reuse - Most Energy Efficient - Withstands High Pressures & Temperatures